#1**+1 **

20) x - 2y = 18 ⇒ x = 18 + 2y

Sub the into the second equation for x and we have

-6(18 + 2y) - 4y = 4 simplify

-108 - 12y - 4y = 4

-108 - 16y = 4 add 108 to both sides

-16y = 112 divide both sides by -16

y = -7

And

x = 18 + 2(-7) = 18 - 14 = 4

CPhill Feb 5, 2019